window.fakeStorage = {
    _data: {},
    setItem: function (id, val) {
        return this._data[id] = String(val)
    },
    getItem: function (id) {
        return this._data.hasOwnProperty(id) ? this._data[id] : undefined
    },
    removeItem: function (id) {
        return delete this._data[id]
    },
    clear: function () {
        return this._data = {}
    }
}
  
function LocalStorageManager() {
    this.bestScoreKey     = "bestScore"
    this.gameStateKey     = "gameState"

    var supported = this.localStorageSupported()
    this.storage = supported ? window.localStorage : window.fakeStorage
}
  
LocalStorageManager.prototype.localStorageSupported = function () {
    var testKey = "test"
    try {
        var storage = window.localStorage
        storage.setItem(testKey, "1")
        storage.removeItem(testKey)
        return true
    } catch (error) {
        return false
    }
}
  
LocalStorageManager.prototype.getBestScore = function () {
    return this.storage.getItem(this.bestScoreKey) || 0
}

LocalStorageManager.prototype.setBestScore = function (score) {
    this.storage.setItem(this.bestScoreKey, score)
}

LocalStorageManager.prototype.getGameState = function () {
    var stateJSON = this.storage.getItem(this.gameStateKey)
    return stateJSON ? JSON.parse(stateJSON) : null
}
  
LocalStorageManager.prototype.setGameState = function (gameState) {
    this.storage.setItem(this.gameStateKey, JSON.stringify(gameState))
}

LocalStorageManager.prototype.clearGameState = function () {
    this.storage.removeItem(this.gameStateKey)
}